Question

The table shows the results of a survey in which separate samples of 400 adults each from the​ East, South,​ Midwest, and West were asked if traffic congestion is a serious problem in their community. The​ 95% confidence interval for the proportion of adults from the East who say traffic congestion is a serious problem is The​ 95% confidence interval for the proportion of adults from the South who say traffic congestion is a serious problem is​ The​ 95% confidence interval for the proportion of adults from the Midwest who say traffic congestion is a serious problem is The​ 95% confidence interval for the proportion of adults from the West who say traffic congestion is a serious problem is

A table consists of four rows containing the following information East 36%; South 33% Midwest 28% West  57%.

​(a) Construct a​ 95% confidence interval for the proportion of adults from the

EastEast

who say traffic congestion is a serious problem.

Answer 1

a)

for east:

sample proportion p̂ =x/n=		0.3600
std error se= √(p*(1-p)/n) =		0.0240
for 95 % CI value of z=		1.96
margin of error E=z*std error   =		0.047
lower bound=p̂ -E                       =		0.313
Upper bound=p̂ +E                     =		0.407

from above 95% confidence interval for population proportion =(0.313,0.407)